JPH03149156A - Cut-in control method and device thereof - Google Patents

Abstract

PURPOSE:To prevent destruction of a tool and damage of a workpiece by stopping cut-in work of the tool for the workpiece when resultant force, synthesized from torque, thrust force and bending force acting on the tool, exceeds a permissible limit value of shearing stress. CONSTITUTION:Torque, thrust force and bending force, applied to a drill 30, are detected by each sensor, and a detecting output of each sensor is input to an arithmetic circuit 34 successively through a detecting circuit 32. In the arithmetic circuit 34, resultant force by detection of each sensor is calculated with a calculated value input to a comparator circuit 36. When the calculated resultant force is in not more than a permissible limit value of shearing stress, a cut-in control in accordance with an operation command is continued, and when the detected resultant force exceeds the permissible limit value of the shearing stress, an overload signal is output from the comparator circuit 36 to execute a control for stopping drive-rotation of a drill 30 or for detaching it from a workpiece 22. Consequently, destruction of the drill 30 and damage of the workpiece 22 can be prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a depth of cut control method and apparatus thereof, and more particularly to a depth of cut control method and apparatus suitable for controlling the depth of cut of a tool in a machine tool.

[Conventional technology]

Conventionally, in machining using drills and milling tools, a method has been adopted in which the cutting depth of the tool is controlled while monitoring the machining state of the workpiece.

When implementing such a control method, it is necessary to
As described in Publication No. 35752, a machine tool is equipped with a mechanism to detect cutting torque and thrust force during hole drilling, and these detection outputs are When a set value is exceeded, an operation is adopted in which the cutting of the drill is stopped or the drill is pulled back.

[Problem to be solved by the invention]

In the above conventional technology, only torque and thrust force are detected, and consideration is not given to bending force (radial force applied to the tip of the drill) and the resultant force of torque, thrust force, and bending force, which have an important effect on drill breakage. If the resultant force of the loads applied to the tool exceeds the maximum shear stress, the tool may break or the workpiece may be damaged.

SUMMARY OF THE INVENTION An object of the present invention is to provide a depth of cut control method and device that can accurately measure the load applied to a tool and stop cutting by the tool before an overload is applied to the tool.

[Means to solve the problem]

In order to achieve the above object, the present invention is a control method that detects the torque, thrust force, and bending force applied to the tool when cutting a workpiece while rotating the tool, and calculates the output of each detection output. This method employs a cutting control method that stops cutting the tool into the workpiece when the resultant force exceeds the allowable limit value of shear stress.

A control device includes a torque detection means for detecting torque applied to a tool that performs a cutting process on a workpiece by rotation, a thrust force detection means for detecting a thrust force applied to the tool, and a bending device for detecting a bending force applied to the tool. a force detection means; a calculation means for calculating the resultant force from the detection outputs of each of the detection means; and a calculation means that compares the calculated value of the calculation means with an allowable limit value of shear stress and outputs an overload signal when the former exceeds the latter. The cutting control device is configured to include a comparison means for adjusting the cutting speed, and a control means for stopping the cutting of the tool into the workpiece in response to an overload signal.

[Effect]

When the workpiece is being cut, the torque, thrust force, and bending force applied to the tool are detected, and when the resultant force of each detection output exceeds the allowable limit value of shear stress, the tool is applied to the workpiece. Since the cutting process is stopped, the tool is prevented from being destroyed and the workpiece is prevented from being damaged.

〔Example〕

Hereinafter, one embodiment of the present invention will be described based on the drawings. In FIG. 1, a transfer device 14 and a machine tool main body 16 are fixed to a base 12 of a machine tool 10.
A slide table 18 is slidably mounted on the main body 16, and a lifting device 20 is fixed to the upper side of the main body 16. A workpiece 22 is placed on the slide table 18, and a spindle 2 is attached to the lifting device M20 via a support 24.
6 is fixed. The spindle 26 is fixed to the support 24 and can be moved up and down in the vertical direction by the lifting device 20. A drill chuck 28 is fixed to the tip side of the spindle 26, and the drill chuck 2
A drill 30 is detachably fixed to 8 as a tool. This spindle 26 has a built-in torque sensor that detects the torque applied to the drill 30, a thrust force sensor that detects the thrust force that is applied to the drill 30, and a bending force sensor that detects the bending force that is applied to the drill 30. The detection output of the sensor is supplied to a detection circuit 32.

The detection signals of each sensor input to the detection circuit 32 are respectively supplied to an arithmetic circuit 34, and the arithmetic circuit 34 applies predetermined coefficients α1 to each detection signal. α2. It is multiplied by α3, and the resultant force of each detection output is calculated from the multiplied value.

Here, when the torque is T, the thrust force is S, and the bending force is F, and these are multiplied by coefficients α1, α2, and α3, the resultant force is expressed by the following equation (1).

K=α1・T+α2・S+α3・F・・・・・・・・・
(1) The calculated value of the resultant force shown in equation (1) above is supplied to the comparator circuit 36. The comparison circuit 36 compares the allowable limit value of shear stress determined below the fracture limit value of the drill 30 with the calculated resultant force calculated by the calculation circuit 34 in association with the resultant force of torque, thrust force, and bending force. ,
When the calculated resultant force exceeds the allowable limit value of shear stress, an overload signal is output to the control device 13B. The control device 38 controls the lifting device 20 according to the operation command.
Transfer equipment M14. It is configured to control the rotational speed of the drill 30, etc., and executes control to stop the rotational drive of the drill 30 or pull the drill 30 back from the workpiece 22 when an overload signal is received. It has become.

In the above configuration, when the control device 38 moves according to the operation command, the elevator g20 and the transfer device 14 are driven by the control signal from the control device 38.

At this time, the drill 30 is rotated by the motor built into the spindle 26 and moved toward the workpiece 22. When the workpiece 22 is cut with the drill 30, the torque, thrust force, and bending force applied to the drill 30 are detected by each sensor, and the detection output of each sensor is sequentially sent to the calculation circuit 34 via the detection circuit 32. is man-powered. The arithmetic circuit 34 calculates the resultant force detected by each sensor, and the calculated value is input to the comparison circuit 368. When the calculated resultant force is less than the allowable limit value of shear stress, the depth of cut control according to the operation command is continued, and when the detected resultant force exceeds the allowable limit value of shear stress, an overload signal is output from the comparison circuit 36, and the drill 306 Rotational drive is stopped or control is performed to separate the drill 30 from the workpiece 22. Therefore, the cutting control by the drill 30 is stopped before the resultant force applied to the drill 30 exceeds the fracture limit value of the drill 30, and the drill 3o is destroyed and the workpiece 2
2 damage can be prevented.

〔Effect of the invention〕

As explained above, according to the present invention, when the resultant force composed of the torque applied to the tool, the thrust force, and the bending force exceeds the allowable limit value of shear stress, cutting of the tool into the workpiece is stopped. This makes it possible to prevent tool breakage and damage to the workpiece.

[Brief explanation of the drawing]

FIG. 1 is an overall configuration diagram showing an embodiment of the present invention. 10... Machine tool, 12... Base, 14... Transfer device. 1 mouth - machine tool body, 18 - slide table. 20... Lifting device, 22... Workpiece, 24...
Support, 26... spindle, 28...-drill chuck. 30...Drill, 32...Detection circuit, 34...Arithmetic circuit, 36...Comparison circuit, 38...Control device.

Claims (1)

[Claims] 1. When cutting a workpiece while rotating the tool, the torque, thrust force, and bending force applied to the tool are detected, and the resultant force of each detection output is the allowable limit value of shear stress. A depth of cut control method that stops the cutting of a tool into a workpiece when the depth exceeds the depth of cut. 2. Torque detection means for detecting torque applied to a tool that performs cutting on a workpiece by rotation; thrust force detection means for detecting thrust force applied to the tool; and bending force for detecting bending force applied to the tool. a detection means; a calculation means for calculating a resultant force from the detection outputs of the respective detection means;
Comparison means that compares the calculated value of the calculation means with the allowable limit value of shear stress and outputs an overload signal when the former exceeds the latter, and stops cutting of the tool into the workpiece upon receiving the overload signal. A cutting control device having a control means for controlling.